Determination of end conditions for NURB surface interpolation

NURB (Non Uniform Rational B-spline) curves and surfaces are being used to solve curve and surface tting problems i.e. where a sequence (or an array) of points is given and then one can nd a NURB curve (or an surface) that interpolates to the given data. In general one has to provide additional information, called end conditions to solve the system of equations in the NURB interpolation problem. Several solutions have been proposed and used for the non rational case. Here, we present some ideas in determining end conditions in the rational case.